Steam-power plant



y 1, 1930. J. A. POWELL 1,769,457

' STEAM POWER PLANT Filed May 14, 1 929 CONDENSER Y LR WIRE/IVE;

ATTORNEY NVENTO2 Patented July I 1930 UNITED sTATEs ejp ATENT OFFICEJAMES POWELL, OF INTERVILLA, PENNSYLVANIA, ASSIGNOR TO FOSTER WHEELERCORPORATION, 'OF NEW YORK, N. A CORPORATION, OF NEW YORK pressure primemovers.

to superheat the steam passing fromlalhigh STEAM-POWER PLANT Applicationfiled May 14, 1929. Serial no, 362,887.

3 My invention relates to steam power plants and particularly to steampower plants having a plurality of prime movers operating withindifferent-ranges of steam pressure. i

For high efficiency, it is desirable that steam of high superheat besupplied to high It is also desirable pressure prime mover to a lowpressure prime mover. Th1s is often done by passing the inter-stagesteam through reheaters,

for example a steam heated reheater and a flue gas heated reheater.arranged 1n serles.

If a high pressure prime mover is bypassed so that steam passesdirect'to a low 7 pressure prime mover, the superheated steam may be toohot for the flue gas reheater.

' Not alone is suchsteam of the superheat of the source but thenecessary throttling inthe by -pass adds heat of superheat. Consequentlyit is advisable to desuperheat the by-passed steam before. its passagethrough the flue gas heated reheater. The 'fluegas heated reheatercannot or should not be bypassed because it is likely to burn out.

In steam'power plants ofthis type, feed water isusually heated by steam.This is accomplished in' the final stage before the flue gas feed'heater by a closed heater, as distinguished from a thoroughfare heater;A thoroughfare heater is one in 1 which steam as steam passesthrough theheater while a closed heater is P one in which the heating steam iscondensed.

I proposeto give such closed heater a double function byusing it merelyasa feed heater during'normal operation and using it as a desuperheaterwhen the high pressure- W prime mover. is .by-rpassedrbyipassinglthe..by-'

- passed steam through it on its way to the reheaters and thus coolingthe by-passed steamsufliciently to prevent excessively high temperature1n the gas reheater. By this means- I obtain the desired and necessaryconditions for the steam with a minimum of steam plant equipment.

The invention is illustrated by means of the accompanying drawingshowing a steam power plant embodying the invention.

the waterin the boiler proper.

what is known as On' the drawing, reference character 10 designates 'aboilerwhich'inay' be of any of various types, suitablylheated and havinga superheater 11 for superheating the steam after the disengagement ofthe steam from A flue 12 leads from the boiler and encloses a flue gasheated reheater or gas reheater 13 and a feed pumped through feed line--16 into the feed water heater and from the feed water heater 'into theboiler through connection'17.

. Boiler steam passes through conduit 18 to 'a high'pressure primemover, illustrated as erators 20and 30 maybe connected to thesameelectric circuit. Instead oftwo sepwater heater 14. Boiler feedwater is r arate turbines, the high and low pressure prime movers may bedifferent sections of a single turbine or other motor. connected todrive a single electric generator or other power consumer. Steam flowthrough the turbines may be controlled in a number of ways; One way isby a centrifugal gov-' 'ernor operated from the shaft of either turbineand arranged to control a supply valve 31 for the high pressure turbine.

Conduits '23 and 24 connect with the steam chamber 32 ofa feedwater-heater 33. Feed.

lsvaterhimsuppliedito. the. feed-water heater by pump 34 and throughconduit 35. The

water circulates through tubes Y 37 within the feed water heater'and isheated by the. steam. Thence the feed water passes through conduit 38and through pump 15 into conduit 16. Condensate is withdrawn from, thefeed water heater by pump 39 and forced into conduit 38.

In conduit '22 is a valve .40. In conduit 23 is a valve 41. In conduit24 is a valve heater 26, throug and the condensate passes 42. Betweenconduit 18 and conduit 21 extends a by-pass conduit 43 in which is a'nection with conduit 21 of by-pass conduit 43 therewith. Thischeck valveis such as to prevent steam from passing through conduit 43 and backthrough conduit 21 into the high ressure turbine exhaust opening.

Steam or heater 26 is taken from the boiler, passes through conduit 49and into a part 50 of the reheater. The steam is'condensed y v y throughconduit 51 back to the boiler.

During normal operation, the main path of flow of steam is throughsuperheater 11, through conduit 18, through high pressure rime mover 19,through conduit 21, through conduit 22, throu h conduit 25, throughreconduit 27, through reheater 13, through conduit 28 and through lowpressure prime mover 29 into the condenser. Condensate from thecondenser asses back to the boiler as feed water. The eed water isheated in feed water heater 33 by steam which is tapped or bled from themain ath of steam' flow through conduit 45. This steam passes throughconduit 23 into space 32 of the feed water heater where it is condensedas it heats the feed water in tubes 37 The amount of this steam.

for heating the feed water in heater 33 is small compared to the amountof steam passing in the main path of flow. Consequently conduit 45 canbeof small size compared to the diameter of the conduits formmg the mainpath of flow. The condensed steam is returned by pump 39 to the boiler.When the high pressure prime mover is by-passed, the main path of flowis from superheater 11, through conduit 18, by-pass conduit 43, throughthe part of conduit 21- between conduit 43 and conduit 23, throughconduit 23, through space 32 of heater 33, through conduit 24, throughconduit 25 and thence on to the low pressure prime mover as in the caseof normal operation. By-pass conduit 43 is of a size totake the amount'of steam flow of the main path. The feed water is heated by the mainpath flowin this case and the. main path steam is desuperheated by thefeed water. By this means the steam, which is .highly superheated as aresult of the original superheating and the throttling through the valveor valves in the by-pass43 is reduced in tem perature so as not topermit excessive temperature in the flue gas heated reheater 13.

In a plant in which the high pressure prime mover is by-passed at timesof decrease of load as in a plant using a steam accumulator connected inparallel with the high pressure prime mover which is charged for poweror other purposes during heavy "fj" load, it may be desirable to controlvalves 40, 41, 42, 44 and 46 automatically. Valve 44 may be connected tothe centrifugal governor for the turbine or turbines so that it openswhen the speed exceeds a given value and mechanismmay be provided.whereby, when valve 44 is opened, valves 40 and 46 are automaticallyclosed and valves 41and 42 automatically opened. For thispur'poseservo-motors for the various valves can be connected to a common relaycontrolled by thespeed of the turbine, or such an arrangement may becontrolled from pressure 1n the steam supply line. In case ofmanualregulation, mechanism may be provided mter-connectingthe valves tooperate to change the steam flow as abpve described when by-pass valve44 is opened.

While I have shown a separate connection 45 for bleeding steam to becondensed in I the feed heater, this connection may be dispensed withinwhich case valve 41 takes over the function of valve 44.

The heater may be provided with a vent for initiating circulation ofsteam therethrough and other supplemental devices customary to plantequipment of this type.

It will be understoodthat wide variations of plant layout are possiblewithin the scope of the invention.

What I claim is:

1. That improvement in the operation of steam plants including a highpressure prime mover, a low pressure prime mover and a feed water heaterand having a main path of steam flow including the high pressure and lowpressure prime movers and a by-pass path of flow around the highpressure .prime mover which comprises withdrawing steam from said mainpath of flow to heat feed water in the feed water heater and 'therebycondensing the withdrawn steam and desuperheating the by-passed steam inthe feed water heater by the cooling effect of feed water withoutcondensing .low pressure motor and. for conducting steam from the highpressure motor into the feed. water heater and means to withdrawcondensed steam from the feed water heater.

conducting feed water through the feed water heater, a conduit forconducting steam heater.

. JAMES A. POWELL.

